3e7d344970
Lumpy reclaim is disruptive. It reclaims a large number of pages and ignores the age of the pages it reclaims. This can incur significant stalls and potentially increase the number of major faults. Compaction has reached the point where it is considered reasonably stable (meaning it has passed a lot of testing) and is a potential candidate for displacing lumpy reclaim. This patch introduces an alternative to lumpy reclaim whe compaction is available called reclaim/compaction. The basic operation is very simple - instead of selecting a contiguous range of pages to reclaim, a number of order-0 pages are reclaimed and then compaction is later by either kswapd (compact_zone_order()) or direct compaction (__alloc_pages_direct_compact()). [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: use conventional task_struct naming] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
104 lines
3 KiB
C
104 lines
3 KiB
C
#ifndef _LINUX_COMPACTION_H
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#define _LINUX_COMPACTION_H
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/* Return values for compact_zone() and try_to_compact_pages() */
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/* compaction didn't start as it was not possible or direct reclaim was more suitable */
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#define COMPACT_SKIPPED 0
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/* compaction should continue to another pageblock */
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#define COMPACT_CONTINUE 1
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/* direct compaction partially compacted a zone and there are suitable pages */
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#define COMPACT_PARTIAL 2
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/* The full zone was compacted */
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#define COMPACT_COMPLETE 3
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#ifdef CONFIG_COMPACTION
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extern int sysctl_compact_memory;
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extern int sysctl_compaction_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *length, loff_t *ppos);
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extern int sysctl_extfrag_threshold;
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extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *length, loff_t *ppos);
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extern int fragmentation_index(struct zone *zone, unsigned int order);
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extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
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int order, gfp_t gfp_mask, nodemask_t *mask);
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extern unsigned long compaction_suitable(struct zone *zone, int order);
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extern unsigned long compact_zone_order(struct zone *zone, int order,
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gfp_t gfp_mask);
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/* Do not skip compaction more than 64 times */
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#define COMPACT_MAX_DEFER_SHIFT 6
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/*
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* Compaction is deferred when compaction fails to result in a page
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* allocation success. 1 << compact_defer_limit compactions are skipped up
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* to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
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*/
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static inline void defer_compaction(struct zone *zone)
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{
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zone->compact_considered = 0;
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zone->compact_defer_shift++;
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if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
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zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
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}
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/* Returns true if compaction should be skipped this time */
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static inline bool compaction_deferred(struct zone *zone)
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{
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unsigned long defer_limit = 1UL << zone->compact_defer_shift;
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/* Avoid possible overflow */
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if (++zone->compact_considered > defer_limit)
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zone->compact_considered = defer_limit;
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return zone->compact_considered < (1UL << zone->compact_defer_shift);
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}
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#else
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static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
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int order, gfp_t gfp_mask, nodemask_t *nodemask)
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{
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return COMPACT_CONTINUE;
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}
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static inline unsigned long compaction_suitable(struct zone *zone, int order)
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{
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return COMPACT_SKIPPED;
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}
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static inline unsigned long compact_zone_order(struct zone *zone, int order,
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gfp_t gfp_mask)
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{
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return 0;
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}
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static inline void defer_compaction(struct zone *zone)
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{
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}
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static inline bool compaction_deferred(struct zone *zone)
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{
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return 1;
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}
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#endif /* CONFIG_COMPACTION */
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#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
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extern int compaction_register_node(struct node *node);
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extern void compaction_unregister_node(struct node *node);
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#else
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static inline int compaction_register_node(struct node *node)
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{
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return 0;
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}
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static inline void compaction_unregister_node(struct node *node)
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{
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}
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#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
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#endif /* _LINUX_COMPACTION_H */
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